Riding Lawnmower Engine

The Damage

Hmmm…this isn’t good.  The lawnmower grenaded.  It looks like the con-rods fused to the crankshaft, and then inertia took over.  One rod broke into about 3 pieces, the other into about 60 smalll fragments.  So, I ordered a couple new con-rods, and a crankshaft.  I could possibly have had the crank machined…but, its only $250 and the machinist would cost $100, and it might not work.  Plus, since the bearings are integral to the con-rod there are only three size options: standard, 0.010 over, and 0.025 over.  What are the odds that he would be able to get that… Given my luck?

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Dissaembly

Time to disassemble and clean it; first remove the carburetor linkage.  Several pictures to make sure I get all the rods, and springs back to the right levers and holes.

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Next the intake, the wire harness is strapped to the intake manifold.  So, there are a couple connectors to remove in order separate the manifold from the block.

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There’s also a connection for the fuel pump.

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Finally, the cylinder heads.  The heads are matched and marked….the pushrods and lifters need to go back into the same positions…so I marked each with a little bit of tape.

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Cleaning

Lots of scrubbing and washing with towels, mineral spirits, toothbrushes.  All shiny clean and ready for reassembly.  Only problem?  One of the wrist-pin springs launched into outer space as I was removing it.  I was 500ms too late in getting my thumb over it to keep it from getting away.  Dang it!  I went back to the parts web site….$0.85 ea, $10 shipping!  I bought 4!

 

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All organized and ready ro go back together….as soon as the wrist pin clips arrive.

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The Damage: Part 2

So, now that I have it clean, and disassembled I can properly inspect the damage.  It’s a little worse that I’d first thought.  As you can see both of the cylinder walls are cracked.  It looks like the cracks are below BDC.  I won’t know for sure until I put the crank back in.  It is ONLY a lawnmower, right?

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